Its decision, which was denounced last night by civil liberties groups, is a rebuff to the European Court of Human Rights (ECHR). The court last year condemned the Government’s policy of retaining DNA samples from all people held by police ? regardless of whether they are found guilty of an offence ? as “blanket and indiscriminate”.

Alan Johnson, the Home Secretary, will set out plans for the genetic profiles of adults who are arrested to be retained for a maximum of six years. It is a minor climb-down by ministers who originally responded to the ECHR ruling by proposing to keep DNA records for up to 12 years for adults suspected of serious crime.

Since the ruling a year ago, more than 400,000 profiles have been added to the database.